The present inention has to do withproviding an electrical interconnect betweenthe bottom and the top of a printed circuit board (PCB). such a connection is called a via.
There are various methods for providing an electrical connection between the bottom and top of a PCB in the prior art. For instance, plated through holes provide an effective via; however, this method of providing vias is relatively expensive. Similarly the insertion of a wire jumper through two holes in a PCB and a soldering the wire to the board on both the top and bottom sides is an effective but expensive method of providing via. The wire jumper insertion method requires hand soldering of the PCB and is therefore costly and time consuming.
Eyelets have been used in the prior art. For instance metal eyelets may be swaged into a hole in a PCB. Sometimes a component lead is inserted t hrough the eyelet before soldering. For a conventional eyelet the top side of the PCB must be soldered in a separate operation if a reliable connection through the PCB is desired.
Similarly, commercially available "solder-through" eyelets, that is special eyelets which utilize capillary action to carry molten solder from the bottom side of a PCB eyelet in a single operation. Component leads are inserted through these eyelets before soldering. The eyelets serves the purpose of strengthening the mechanicalconnection of the component to the PCB.
The major drawback of using eyelets for vias in the prior art has been the inability to provide a reliable electrical joint. Thermal expansion due to tmperature cycling often causes joints to crack resulting in elecrical failure.